Motor Learning Abilities in Adults who Stutter by Kimberly Rose Bauerly A thesis submitted in ...

230 Pages·2012·1.09 MB·English

Motor Learning Abilities in Adults who Stutter

by

Kimberly Rose Bauerly

A thesis submitted in conformity with the requirements
for the degree of Speech- Language Pathology
Department of Speech- Language Pathology
University of Toronto

© Copyright by Kimberly Rose Bauerly (2012)
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Motor Learning Abilities in Adults who Stutter

Doctor of Philosophy, 2012
Kimberly Rose Bauerly

Department of Speech-Language Pathology
University of Toronto

Abstract
This dissertation is comprised of three studies investigating the hypothesis that people who stutter
(PWS) differ from people who do not stutter (PNS) in their motor skill learning abilities. The first study
in this dissertation examined the ability to learn a novel sequential speech task following a 24-h retention
period. Despite slower sequence durations compared to the PNS, PWS showed the ability to retain what
they had learned for all measured variables on day one and following a 24-h consolidation period. The
second study in this dissertation examined the ability to learn a sequential finger tapping task by
observing the ability to produce the sequence under both tests of retention and interference. For tests of
retention, PWS showed the ability to retain improvements in performance for all measured variables,
albeit at slower speeds compared to PNS. For tests of interference, a significant interaction for reaction
time and sequence duration revealed that PNS’ performance reached a relative plateau while PWS’
performance continued to show improvement.
The third study in this dissertation investigated the extent to which individual differences in
motor learning are associated with differences in stuttering treatment outcome. PWS participating in an
intensive fluency treatment program were assessed for their working memory ability and their motor
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learning performance on a syllable reading and finger tapping task. Treatment success was measured at
pre-treatment, post-treatment and six months follow-up using percent syllables stuttered, introspective
clinical characteristics (OASES; Yaruss, 2010) and fluency effort. The relationship between motor
learning and treatment outcome was examined using multiple regression analyses. Results did not support
the hypothesis that the ability to learn a simple speech and nonspeech motor task is predictive of
treatment outcome. Although treatment proved successful as evidenced by percent syllables stuttered and
OASES scores, scores of fluency effort indicated that participants had not automated their newly learned
fluency skills when speaking in everyday conversations.
Together, these studies do not support the hypothesis of a motor learning deficit in PWS but
rather support the assumption of limited motor abilities. Limited motor abilities are discussed as having
implications to stuttering treatment outcome.
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Acknowledgments
It has been a great pleasure working with the faculty, staff and students at the University of
Toronto. I could not have succeeded without the invaluable support of a several. Without these
supporters, especially the select few I’m about to mention, I may not have gotten to where I am today. I’d
like to give a heartfelt, special thanks to my supervisor and mentor, Dr. Luc De Nil. He has been
motivating, encouraging, and enlightening. His patience, flexibility, genuine caring and concern, and
relaxed demeanor have been appreciated. I am very grateful to the remaining members of my dissertation
committee, Dr. Elizabeth Rochon and Dr. Pascal van Lieshout. I appreciate their insightful comments
and constructive criticism regarding both theoretical and methodological issues surrounding my research.
They often posed questions to me that were very challenging, which allowed me to reach my maximum
potential in learning and I am thankful for that. I have also been very fortunate to have had the
opportunity to learn from Dr. Robert Kroll. His academic support and input in helping me develop my
third study has been greatly appreciated.
My deepest gratitude goes to Sophie Lafaille who has known the answer to every question I’ve
ever asked her regarding lab equipment and computer problems. I couldn’t have completed all the
required paperwork and delivered it to the correct place without her. Thank you Sophie, you shall always
be remembered as a smiling face and a warm and friendly heart. I am also very thankful to Sara Smits-
Bandstra, Deryl Beal and Aravind Namasivayam who were always there for me to proofread a paper,
answer statistical problems or hash out an idea with me. Most of all, they provided the encouragement I
needed to continue on. My gratitude is also extended to Marni Grotell for her help with data collection as
well as Neil Mathews, Anna Arulampalam, and Emily Dixon for their help in performing the reliability
measures. I wish to thank all of the considerate individuals who devoted their time to participate in my
studies. I am also grateful to the friends I have met on this journey, especially to Stacey Skoretz, who has
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become a good friend to me and has helped me stay sane through these years. It has been a privilege
getting to know her.
Most importantly, none of this would be possible without the love and support from my family.
My parents have taught me about hard work and self-respect, and about persistence. Mom, especially,
was a great role model of resilience, strength and character. Both have always expressed how proud they
are of me and how much they love me. I’d also like to extend deep appreciation to my parents- in – law
who provided me with the financial support needed to embark on this endeavor.
Finally, this dissertation is dedicated to my husband, Brad Bauerly, and two beautiful daughters. I
must acknowledge with tremendous and deep thanks my husband, who through love, support and belief in
me, I’ve been able to complete this dissertation. I am also indebted to my beautiful daughter Addison, for
the very special person she is. She has provided me with so many happy and beautiful memories
throughout this journey. And last but not least, Lauren, my little love bug, who has blessed our lives
during the final stages of this journey.
These studies were funded by a grant by the Natural Sciences and Engineering Research Council
of Canada (RGPIN 105626-04) granted to Dr. Luc De Nil. I am grateful for the financial support I
received by the University of Toronto Open Fellowship Award.
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CONTENTS

Abstract..........................................................................................................................................................ii
Acknowledgments ........................................................................................................................................iv
List of Tables ...............................................................................................................................................xi
Table of Figures .........................................................................................................................................xiii
List of Appendices ………………………………………………………………………………………xvii
CHAPTER I INTRODUCTION AND LITERATURE REVIEW ...............................................................1
Introduction ......................................................................................................................................1
Incidence and Prevalence .................................................................................................................1
Developmental Stuttering ................................................................................................................1
Motor Abilities and Developmental Stuttering ................................................................................2
Neurophysiology and Developmental Stuttering .............................................................................5
Neuroanatomy and Developmental Stuttering .................................................................................8
Genetics and Developmental Stuttering ..........................................................................................9
Environment and Developmental Stuttering ..................................................................................11
Conclusions ....................................................................................................................................13
CHAPTER II MOTOR PRACTICE AND LEARNING ............................................................................14
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Introduction ....................................................................................................................................14
Motor Skill Learning ......................................................................................................................15
Attention and Automaticity ............................................................................................................16
Working Memory and Motor Learning .........................................................................................17
Stages of Motor Learning ..............................................................................................................18
Measuring Motor Skill Learning ...................................................................................................21
Schema Theory ..............................................................................................................................25
Schema Theory and Sequence Skill Learning ...............................................................................26
Conclusions ....................................................................................................................................28
CHAPTER III MOTOR PRACTICE AND LEARNING IN PWS.............................................................29
Introduction ....................................................................................................................................29
Motor Practice and Developmental Stuttering ...............................................................................29
Motor Learning and Developmental Stuttering .............................................................................31
Treatment Effects ...........................................................................................................................36
Conclusions ....................................................................................................................................37
Research Questions ........................................................................................................................38
CHAPTER IV SPEECH SEQUENCE SKILL LEARNING IN ADULTS WHO STUTTER ...................39
Abstract ..........................................................................................................................................39
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Introduction ....................................................................................................................................40
Present Investigation and Objectives..............................................................................................43
Methods ..........................................................................................................................................47
Statistical Analysis .........................................................................................................................48
Results ............................................................................................................................................49
Discussion ......................................................................................................................................60
Conclusions ....................................................................................................................................64
CHAPTER V NONSPEECH SEQUENCE SKILL LEARNING IN
ADULTS WHO STUTTER ...........................................................................................................65
Abstract ..........................................................................................................................................65
Introduction ....................................................................................................................................66
Present Investigation and Research Questions ..............................................................................73
Methods ..........................................................................................................................................73
Statistical Analysis......................................................................................................................... 74
Results ............................................................................................................................................81
Discussion ......................................................................................................................................92
Conclusions ..................................................................................................................................100
CHAPTER VI MOTOR LEARNING ABILITIES IN ADULTS WHO STUTTER:
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PREDICTIVE FACTORS TO LONG TERM TREATMENT OUTCOME ...............................102
Abstract ........................................................................................................................................102
Introduction ..................................................................................................................................102
Present Investigation and Research Questions ............................................................................111
Methods ........................................................................................................................................111
Statistical Analysis........................................................................................................................122
Results ..........................................................................................................................................123
Discussion ....................................................................................................................................136
Conclusions...................................................................................................................................144
CHAPTER VII DISCUSSION .................................................................................................................145
A Review of the Speech and Nonspeech Sequence Skill Learning Studies: Evidence
of Limitations in Motor Ability....................................................................................................145
A Review of Chapter 6: Motor learning abilities in adults who stutter: Predictive
Factors to Long Term Treatment Outcome ..................................................................................151
Motor Skill Limitations in PWS ..................................................................................................152
Implications for Treatment ..........................................................................................................160
Limitations and Future Directions ...............................................................................................163
Conclusions ..................................................................................................................................167
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Appendices …………………………….…………………………………………….………….169
References ....................................................................................................................................175